Reduced Layer Keyboard Stack-Up Using Flexible Substrate
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Solution Overview
Problem
Conventional keyboard assemblies are thick due to multiple layers, which is undesirable for integration with small or thin form factor electronic devices.
Innovation Solution
A reduced layer keyboard stack-up using a flexible substrate with an in-plane switch and an optional light source, where the dome actuates to bridge contacts on the switch, reducing the overall thickness and allowing for additional structural support without increasing the device's thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If multiple layers are included in the keyboard assembly to provide structural support and functionality, then the structural integrity and functional capability are improved, but the overall thickness of the keyboard assembly increases
Solution Approach 1:
The patent combines multiple functional layers into a single integrated flexible substrate that contains both the in-plane switch contacts and light source elements. This merging eliminates the need for separate plastic layers and spacers, reducing the overall keyboard assembly thickness while maintaining structural integrity and functional capability through the integrated design of the flexible substrate.
2Reliability
If conventional dome switch with multiple layers is used, then the switch functionality is reliable, but the keyboard assembly thickness increases making it unsuitable for thin form factor devices
Solution Approach 1:
The patent replaces the conventional multi-layer mechanical dome switch structure with an in-plane switch mechanism integrated into a flexible substrate. The in-plane switch uses lateral movement of conductive elements within the same plane rather than vertical layer deflection, eliminating the need for thick spacer layers and multiple plastic sheets while maintaining reliable switch functionality.
3Strength
If additional structural support is added to the keyboard assembly, then the structural strength is improved, but the thickness of the device increases
Solution Approach 1:
The patent employs a flexible substrate that provides structural support through its inherent material properties and integrated circuit board construction rather than through thick rigid layers. The flexible substrate maintains keyboard structural integrity while enabling thin form factor design by utilizing the strength of the integrated circuit board and flexible material composition instead of relying on multiple thick plastic layers.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables a thinner keyboard assembly that can be manipulated and integrated into small form factor electronic devices while maintaining functionality and structural support.
Implementation Method 1
The dome is adapted to cause the in-plane switch to conduct a signal in response to actuation of the dome
Implementation Method 2
A conductive material positioned above the switch bridges the at least two contacts of the switch
Data Source
AI summary
Disclosed herein is a stack-up for an input device. The stack-up may include a flexible substrate having a switch and a light source. The switch has at least two contacts that are bridged in response to actuation of a dome that is positioned above the switch. The flexible substrate includes a signal trace for detecting the actuation of the dome and a power trace for providing power to the light source.